Hi friends. Today found a real bargain. A man owned a peavey mark IV and a cab Peavey 215 BW. He bought the team in 1987 and use for 3 years. Then the peavey was stored until it has for sale. I know, bought it because I actually bought a 1987 amp new in 2010 lol. But I found a poblem. The speakers make a weird vibe, it seemed that vibrating the fabric front. I've removed the fabric and even Keep doing. I thought... could be the tightening of the cone, because for many years without use, so I connected my mp3 and I'm leaving through the amplifier. Has anyone come up with something similar or can know that happens? Thank you all.